STEVAL-ISA055V2
0.7 A / 3.3 V synchronous buck converter
with enable function based on the ST1S12XX
Data Brief
Features
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Step-down current mode PWM (1.7 MHz) DC-
DC converter
Fixed output voltage 3.3 V
0.7 A output current capability
3% DC output voltage tolerance
Synchronous rectification
Enable function
Internal soft-start
Typical efficiency: > 90%
Non switching quiescent current: max 600 µA
over temperature range
R
DS(on)
typ. 250 mΩ and 400 mΩ
Uses tiny capacitors and inductors
STEVAL-ISA055V2
Description
This demonstration board is based on the
ST1S12 family of synchronous step-down DC-DC
converters optimized for powering low-voltage
digital cores in HDD (hard disk drive) applications,
and is generally used to replace high-current
linear solutions when power dissipation may
cause high heating of the application
environment.
It provides up to 0.7 A over an input voltage range
of 2.5 V to 5.5 V. A high switching frequency of 1.7
MHz allows the use of tiny surface-mount
components. A resistor divider to set the output
voltage value, an inductor, and two capacitors are
required for the adjustable version, while only an
inductor and 2 capacitors are needed for the 1.2 V
and 1.8 V fixed version.
A low output ripple is guaranteed by the current
mode PWM topology and by the use of low ESR
surface-mount ceramic capacitors.
The ST1S12 device is thermal protected and
current limited to prevent damage due to
accidental short-circuit. This family of products is
available in the TSOT23-5L package.
September 2008
Rev 1
1/4
www.st.com
4
For further information contact your local STMicroelectronics sales office.
STEVAL-ISA055V2
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